Hebbal lake still exists, and does see migrant birds like painted storks and pelicans every winter. You can see for yourself, and BngBirds visits Hebbal Lake on the first Sunday of every month to see birds. The migrant birds that do visit India in winter come from colder parts of Asia and Europe, not Australia btw.

Yes many lakes are destroyed in Bangalore and there are no sparrows. Its doubtful that mobile towers have anything to do with it though.